A woman-worker had already opened the door and was pulling a lever.

As though by magic, a bunch of castings, wired together, came travelling out of their heat bath and were immediately lowered into a large tank which held the tempering liquid.
"What would have happened if the oven hadn't been opened when the white light appeared ?" asked another of the visitors.
"In five minutes a red lamp would have been automatically lighted," said Mary "-- a signal for the forewoman to come and take charge of the oven." "And suppose the red lamp had been disregarded ?" "In five minutes more an alarm bell would have started.

You would have heard it over half the factory--and it would have kept ringing until the superintendent herself had come and stopped it with a key which only she is allowed to carry." "Is that the bell now ?" he asked, as a mellow chime came from one of the distant buildings.
"No," smiled Mary, listening, "that's the lunch bell.

In another ten minutes I shall have a surprise for you." At the end of that time, they made their way to the dining room, which was already filled with eager women.

In one corner was a private room, glass-partitioned.